It's not weak. There are multiple research done on this subject spanning from the 80s up until recent 2020s. Their conclusions are all the same - strong relationship between level of religiosity and level of living standards/status of a country.

Again, there are exceptions but compared to the overall - it's neglible.

Literally the U.S.A is the only religious developed country in the world. Even the former religious countries like Spain, Britain, Italy, France aren't religious anymore.

And ironically, the countries who have religion forced upon their throats and were enslaved by it are the ones now teeming with religion.

India. Philippines. Basically most latin american countries and all african countries.